Critical plane-energy based approach for assessment of biaxial fatigue damage where the stress-time axes are at different frequencies

Abstract

Abstract A new fatigue parameter has been developed to assess the fatigue lives under in-phase and out-of-phase biaxial constant amplitude fatigue stressing where the stresses are at different frequencies. In this parameter, the normal and shear stress and strain ranges have been calculated from the largest stress and strain Mohr's circles. The total damage accumulation in a block loading history has been calculated from the summation of the normal and shear energies on the basis of a cycle-by-cycle analysis. The normal and shear energies used in this parameter are divided by the tensile and shear fatigue properties, respectively, and the proposed parameter, unlike many other parameters, does not use an empirical fitting factor. The proposed fatigue parameter has successfully correlated biaxial fatigue lives of thin-walled EN24 steel tubular specimens tested under in-phase and out-of-phase biaxial fatigue stressing where stresses were at different frequencies and included mean values.